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<div class="header">
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<a href="#func-members">Functions</a>  </div>
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<div class="title">Bilinear Interpolation<div class="ingroups"><a class="el" href="group__groupInterpolation.html">Interpolation Functions</a></div></div>  </div>
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<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="func-members"></a>
Functions</h2></td></tr>
<tr class="memitem:ga887756dbbe013d0a15b987836a787677"><td class="memItemLeft" align="right" valign="top">__STATIC_FORCEINLINE <a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a>&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__BilinearInterpolate.html#ga887756dbbe013d0a15b987836a787677">arm_bilinear_interp_f32</a> (const <a class="el" href="structarm__bilinear__interp__instance__f32.html">arm_bilinear_interp_instance_f32</a> *S, <a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> X, <a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> Y)</td></tr>
<tr class="memdesc:ga887756dbbe013d0a15b987836a787677"><td class="mdescLeft">&#160;</td><td class="mdescRight">Floating-point bilinear interpolation.  <a href="#ga887756dbbe013d0a15b987836a787677">More...</a><br/></td></tr>
<tr class="separator:ga887756dbbe013d0a15b987836a787677"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:gaefe4731017e8b9ac652e5fea57cb1fa5"><td class="memItemLeft" align="right" valign="top">__STATIC_FORCEINLINE <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a>&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__BilinearInterpolate.html#gaefe4731017e8b9ac652e5fea57cb1fa5">arm_bilinear_interp_q31</a> (<a class="el" href="structarm__bilinear__interp__instance__q31.html">arm_bilinear_interp_instance_q31</a> *S, <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> X, <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> Y)</td></tr>
<tr class="memdesc:gaefe4731017e8b9ac652e5fea57cb1fa5"><td class="mdescLeft">&#160;</td><td class="mdescRight">Q31 bilinear interpolation.  <a href="#gaefe4731017e8b9ac652e5fea57cb1fa5">More...</a><br/></td></tr>
<tr class="separator:gaefe4731017e8b9ac652e5fea57cb1fa5"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:ga56fe34273ffb422f428b1d9feeffe0ea"><td class="memItemLeft" align="right" valign="top">__STATIC_FORCEINLINE <a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a>&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__BilinearInterpolate.html#ga56fe34273ffb422f428b1d9feeffe0ea">arm_bilinear_interp_q15</a> (<a class="el" href="structarm__bilinear__interp__instance__q15.html">arm_bilinear_interp_instance_q15</a> *S, <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> X, <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> Y)</td></tr>
<tr class="memdesc:ga56fe34273ffb422f428b1d9feeffe0ea"><td class="mdescLeft">&#160;</td><td class="mdescRight">Q15 bilinear interpolation.  <a href="#ga56fe34273ffb422f428b1d9feeffe0ea">More...</a><br/></td></tr>
<tr class="separator:ga56fe34273ffb422f428b1d9feeffe0ea"><td class="memSeparator" colspan="2">&#160;</td></tr>
<tr class="memitem:ga1230bb062f6d8614db10b37ba7c9a161"><td class="memItemLeft" align="right" valign="top">__STATIC_FORCEINLINE <a class="el" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263">q7_t</a>&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group__BilinearInterpolate.html#ga1230bb062f6d8614db10b37ba7c9a161">arm_bilinear_interp_q7</a> (<a class="el" href="structarm__bilinear__interp__instance__q7.html">arm_bilinear_interp_instance_q7</a> *S, <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> X, <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> Y)</td></tr>
<tr class="memdesc:ga1230bb062f6d8614db10b37ba7c9a161"><td class="mdescLeft">&#160;</td><td class="mdescRight">Q7 bilinear interpolation.  <a href="#ga1230bb062f6d8614db10b37ba7c9a161">More...</a><br/></td></tr>
<tr class="separator:ga1230bb062f6d8614db10b37ba7c9a161"><td class="memSeparator" colspan="2">&#160;</td></tr>
</table>
<a name="details" id="details"></a><h2 class="groupheader">Description</h2>
<p>Bilinear interpolation is an extension of linear interpolation applied to a two dimensional grid. The underlying function <code>f(x, y)</code> is sampled on a regular grid and the interpolation process determines values between the grid points. Bilinear interpolation is equivalent to two step linear interpolation, first in the x-dimension and then in the y-dimension. Bilinear interpolation is often used in image processing to rescale images. The CMSIS DSP library provides bilinear interpolation functions for Q7, Q15, Q31, and floating-point data types.</p>
<p><b>Algorithm</b> </p>
<dl class="section user"><dt></dt><dd>The instance structure used by the bilinear interpolation functions describes a two dimensional data table. For floating-point, the instance structure is defined as: <pre>
  typedef struct
  {
    uint16_t numRows;
    uint16_t numCols;
    float32_t *pData;
} <a class="el" href="structarm__bilinear__interp__instance__f32.html" title="Instance structure for the floating-point bilinear interpolation function. ">arm_bilinear_interp_instance_f32</a>;
</pre></dd></dl>
<dl class="section user"><dt></dt><dd>where <code>numRows</code> specifies the number of rows in the table; <code>numCols</code> specifies the number of columns in the table; and <code>pData</code> points to an array of size <code>numRows*numCols</code> values. The data table <code>pTable</code> is organized in row order and the supplied data values fall on integer indexes. That is, table element (x,y) is located at <code>pTable[x + y*numCols]</code> where x and y are integers.</dd></dl>
<dl class="section user"><dt></dt><dd>Let <code>(x, y)</code> specify the desired interpolation point. Then define: <pre>
    XF = floor(x)
    YF = floor(y)
</pre> </dd></dl>
<dl class="section user"><dt></dt><dd>The interpolated output point is computed as: <pre>
 f(x, y) = f(XF, YF) * (1-(x-XF)) * (1-(y-YF))
          + f(XF+1, YF) * (x-XF)*(1-(y-YF))
          + f(XF, YF+1) * (1-(x-XF))*(y-YF)
          + f(XF+1, YF+1) * (x-XF)*(y-YF)
</pre> Note that the coordinates (x, y) contain integer and fractional components. The integer components specify which portion of the table to use while the fractional components control the interpolation processor.</dd></dl>
<dl class="section user"><dt></dt><dd>if (x,y) are outside of the table boundary, Bilinear interpolation returns zero output. </dd></dl>
<h2 class="groupheader">Function Documentation</h2>
<a class="anchor" id="ga887756dbbe013d0a15b987836a787677"></a>
<div class="memitem">
<div class="memproto">
      <table class="memname">
        <tr>
          <td class="memname">__STATIC_FORCEINLINE <a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a> arm_bilinear_interp_f32 </td>
          <td>(</td>
          <td class="paramtype">const <a class="el" href="structarm__bilinear__interp__instance__f32.html">arm_bilinear_interp_instance_f32</a> *&#160;</td>
          <td class="paramname"><em>S</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype"><a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a>&#160;</td>
          <td class="paramname"><em>X</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype"><a class="el" href="arm__math_8h.html#a4611b605e45ab401f02cab15c5e38715">float32_t</a>&#160;</td>
          <td class="paramname"><em>Y</em>&#160;</td>
        </tr>
        <tr>
          <td></td>
          <td>)</td>
          <td></td><td></td>
        </tr>
      </table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an instance of the interpolation structure. </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">X</td><td>interpolation coordinate. </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">Y</td><td>interpolation coordinate. </td></tr>
  </table>
  </dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>out interpolated value. </dd></dl>

</div>
</div>
<a class="anchor" id="ga56fe34273ffb422f428b1d9feeffe0ea"></a>
<div class="memitem">
<div class="memproto">
      <table class="memname">
        <tr>
          <td class="memname">__STATIC_FORCEINLINE <a class="el" href="arm__math_8h.html#ab5a8fb21a5b3b983d5f54f31614052ea">q15_t</a> arm_bilinear_interp_q15 </td>
          <td>(</td>
          <td class="paramtype"><a class="el" href="structarm__bilinear__interp__instance__q15.html">arm_bilinear_interp_instance_q15</a> *&#160;</td>
          <td class="paramname"><em>S</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype"><a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a>&#160;</td>
          <td class="paramname"><em>X</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype"><a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a>&#160;</td>
          <td class="paramname"><em>Y</em>&#160;</td>
        </tr>
        <tr>
          <td></td>
          <td>)</td>
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        </tr>
      </table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an instance of the interpolation structure. </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">X</td><td>interpolation coordinate in 12.20 format. </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">Y</td><td>interpolation coordinate in 12.20 format. </td></tr>
  </table>
  </dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>out interpolated value. </dd></dl>

</div>
</div>
<a class="anchor" id="gaefe4731017e8b9ac652e5fea57cb1fa5"></a>
<div class="memitem">
<div class="memproto">
      <table class="memname">
        <tr>
          <td class="memname">__STATIC_FORCEINLINE <a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a> arm_bilinear_interp_q31 </td>
          <td>(</td>
          <td class="paramtype"><a class="el" href="structarm__bilinear__interp__instance__q31.html">arm_bilinear_interp_instance_q31</a> *&#160;</td>
          <td class="paramname"><em>S</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype"><a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a>&#160;</td>
          <td class="paramname"><em>X</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype"><a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a>&#160;</td>
          <td class="paramname"><em>Y</em>&#160;</td>
        </tr>
        <tr>
          <td></td>
          <td>)</td>
          <td></td><td></td>
        </tr>
      </table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an instance of the interpolation structure. </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">X</td><td>interpolation coordinate in 12.20 format. </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">Y</td><td>interpolation coordinate in 12.20 format. </td></tr>
  </table>
  </dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>out interpolated value. </dd></dl>

</div>
</div>
<a class="anchor" id="ga1230bb062f6d8614db10b37ba7c9a161"></a>
<div class="memitem">
<div class="memproto">
      <table class="memname">
        <tr>
          <td class="memname">__STATIC_FORCEINLINE <a class="el" href="arm__math_8h.html#ae541b6f232c305361e9b416fc9eed263">q7_t</a> arm_bilinear_interp_q7 </td>
          <td>(</td>
          <td class="paramtype"><a class="el" href="structarm__bilinear__interp__instance__q7.html">arm_bilinear_interp_instance_q7</a> *&#160;</td>
          <td class="paramname"><em>S</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype"><a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a>&#160;</td>
          <td class="paramname"><em>X</em>, </td>
        </tr>
        <tr>
          <td class="paramkey"></td>
          <td></td>
          <td class="paramtype"><a class="el" href="arm__math_8h.html#adc89a3547f5324b7b3b95adec3806bc0">q31_t</a>&#160;</td>
          <td class="paramname"><em>Y</em>&#160;</td>
        </tr>
        <tr>
          <td></td>
          <td>)</td>
          <td></td><td></td>
        </tr>
      </table>
</div><div class="memdoc">
<dl class="params"><dt>Parameters</dt><dd>
  <table class="params">
    <tr><td class="paramdir">[in,out]</td><td class="paramname">S</td><td>points to an instance of the interpolation structure. </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">X</td><td>interpolation coordinate in 12.20 format. </td></tr>
    <tr><td class="paramdir">[in]</td><td class="paramname">Y</td><td>interpolation coordinate in 12.20 format. </td></tr>
  </table>
  </dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>out interpolated value. </dd></dl>

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